(Hint: the more energy from the Sun that Earth gets, the more warmth Earth receives, the more
abundant the wheat crops, the lower the price of wheat; the less energy from the Sun, the less warmth, the more wheat crop failures, the higher the wheat price.)
They particularly fail for the poor, whose limited market resources leave them vulnerable to the whims of the wealthy (as for example, in the great Irish potato famine in which thousands starved to death while
abundant Irish
wheat crops were sold to England for English bread).